In one of its aspects this invention pertains to retroreflective sheeting. In a more specific aspect the invention relates to flexible, reflective roll-up signs intended for use in conjunction with various types of flexible sign support stands.
Flexible, reflective, roll-up signs are used to provide traffic control information temporarily, during short-term periods, such as for highway mowing, small construction jobs, survey crews, utility crews, highway line striping crews, tree trimming crews, and cable television crews. They are in the form of retroreflective sheeting having pockets which fit on a stand which can be collapsed so that the sign can be rolled up after use.
Retroreflective sheeting is well known, as exemplified in U.S. Pat. Nos. 4,763,985, 4,511,210, 4,367,920, 4,075,049, 4,025,674, 3,288,618 and 3,190,178, the disclosures of which are incorporated by reference herein. However, for the most part the sheeting is provided as rolls with an adhesive backing for application to metal road signs, license plates and the like. In the fabrication of such sheets, no thought has been given to problems other than reflectivity and flexibility, such as those presented by roll-up signs of the type shown in FIG. 3. Such roll-up signs as sign 2 must be provided with means such as pockets 4 in order to be held by a supporting means such as cross arms 6 of collapsible stand 7. Hence in addition to weather resistance, durability and foldability, means for attaching pockets must be devised.
For the most part, plastics cannot be sewn. The resulting needle holes weaken or tear the sewn area so that the pocket quickly pulls away. The usual method for providing such pockets, then, has been to attach them by fusion, using heated die elements in a process similar to that used in U.S. Pat. No. 3,190,178 to produce the high brilliancy hermetically sealed bead pockets. However the deformation which occurs when the heated die is impressed to bring about the heat fluidization usually weakens the plastic. In roll-up signs made by fusion processes, pockets tear out, or at least partially out and, as a result of exposure to the atmosphere, lose their brilliance. Roll-up signs, therefore, are subject to improvement. By this invention, a long-lasting roll-up sign is provided which retains its brilliancy with age, and which has durable pockets which are not weakened by stitching, nor deformed by thermoforming.